Formal verification of embedded systems based on CFSM networks

Both timing and functional properties are essential to characterize the correct behavior of an embedded system. Verification is in general performed either by simulation, or by bread-boarding. Given the safety requirements of such systems, a formal proof that the properties are indeed satisfied is highly desirable. In this paper, we present a formal verification methodology for embedded systems. The formal model for the behavior of the system used in POLIS is a network of Codesign Finite State Machines (CFSM). This model is translated into automata, and verified using automata-theoretic techniques. An industrial embedded system is verified using the methodology. We demonstrate that abstractions and separation of timing and functionality is crucial for the successful use of formal verification for this example. We also show that in POLIS abstractions and separation of timing and functionality can be done by simple syntactic modification of the representation of the system.